Johan Bornman Posted June 3, 2009 Posted June 3, 2009 Workshop Stories - A fortnight of bad wheels<?: prefix = o ns = "urn:schemas-microsoft-com:office:office" /> The most exciting thing that happened in the Yellow Saddle workshop in the last two weeks was a limp Campag Ergo shifter. Lots of springs, wheels and ratchets to make life exciting. But that?s for another story. I want to talk about the boring stuff, the stuff that affects most bike riders at one stage or another ? bad wheels. Case 1: The wheel that no-one else could fix. Sent to me all the way from Gaberone, was a MTB wheel that persistently broke spokes, refused to stay true and was at the centre of a row between several bike shops and bike owner. Having learnt a lesson all over again from Case 2 below, I fiddled with some random spokes and discovered that some nipples won?t turn at all. Out came the cable cutter and snap snap snap went the spokes. A fresh start is all I had patience for. By cutting out the spokes I had the perfect opportunity to do a post-mortem inspection of the wheel?s centre of truth ? the relative position of all the spokes in the nipples as they were when the wheel was last worked on. The picture was dismal. It is not unusual for an old wheel to show signs of previous repair ? spokes from a different manufacturer or even different coloured spokes. However, this one showed an extraordinary spoke length discrepancy, almost as if someone just grabbed a bunch of random spokes and built the wheel. The result is that some are completely bottomed out, limiting the ultimate tension on the wheel and a wheel with too low tension, hence the broken spokes. Some spokes barely engaged, others poked right through the nipples with no scope for further adjustment.Solution: Start fresh and build with the correct lengths and stress relieve. I bet the customer never comes back again ? for all the right reasons. Case 2: The Zipp that broke spokes two weeks after a re-build. This particular wheel is an old customer of mine. Way back when I built it for the owner onto a Powertap hub. It was an impossible wheel from the start and initially broke spokes. The spoke arrival angle was just too steep for the Zipp?s relatively large cross section where it is drilled. A build with a Zipp deep section rim on a large flange hub can be marginally improved by filing a better path for the nipple in the thick triangular section of the rim on the left. It also sends shivers down the spines of Zipp distributors. One day they'll understand. It was drilled for a Zipp hub that?s much, much smaller than the Powertap hub. However, I?ve re-worked the wheel after the initial problems, filing the holes so that they follow the spoke line more closely and performed one or two proprietary tricks to increase the spoke life in a wheel that was a Frankenstein to start off with. The owner had a cat-eye incident that pulverised is rim during a championship week somewhere. The wheel was rebuilt on site with a new rim and new spokes. Two weeks later it landed on my operating table with all sorts of problems. Zipp spokes cost R25 each so random cutting is not an option. I removed them one in what is a tedious process since the nipples tend to fall inside the cavity never to want to come out again. Nevertheless, once I had them all out I bunched them together, stamped the J-bend ends level and examined the other side, revealing an assortment of lengths. Level on the bend side but not so even on the other side...a variety of lengths. Again, the builder simply grabbed a random bunch of spokes and built ? possibly under pressure at the event to get the wheel done. However, he should not have replaced the spokes and did a standard rim transplant instead, moving the spokes one by one to the new rim taped alongside the old one. Solution: File the rim, rebuild with brand new spokes and apply secret tricks. Case 3: The bad, bad Shimano WH-R600. This particular wheel design was perpetrated by a Japanese engineer with a hangover from saki. If you know saki, you can imagine the poor man?s state of mind. The nipples are at the hub. They?re recessed into thick flanges and designed to fit exactly into their recesses, with no option for sideways movement. These are crazy wheels designed by a hung-over, vindictive Japanese engineer. Not only does it seriously tests the builder?s patience when working with the wheel (adjacent spokes are adjusted in totally incongruent places on the wheel), but if the nipples are not exactly aligned with the direction of the spokes, it spells trouble. This particular wheel is also an old friend of mine. I rebuilt it some months back and soon, too soon, the owner had to phone his girlfriend to come and fetch him at Hartebeespoort where he was stuck with a broken spoke. Now, one should never ride too far from home on boutique wheels like these since a broken spoke spells the end of the ride. Better wheels will allow you to just open the brake calliper and carry on riding. No one listens to me in anyway, so off they go. The quick spoke breakage puzzled me a bit but when I eventually had the wheel I could see that the spokes broke at the threads ? a classic sign that the spokes and nipples are not perfectly aligned. But how could that be? The wheel was designed to be straight-pull and there?s no room for adjustment. I removed the spokes and discovered that most of them are bent where they enter the nipple. This means the wheel?s drilling is wrong. It is a serious design fault and/or manufacturing fault and this wheel will NEVER give decent spoke life. Note the bend in spokes 1, 4and 5. These are destined to break inside the first thread.These bends were set into the spokes during the build at the angle dictated by the rigid nipple in the hub flange. Solution: Replace the affected side with standard straight-pull spokes that cost R9-00 each instead of R30 each for the Shimano spokes and tell the owner that he?s the owner of a rubbish wheel. I?ve done what I can. Johan Bornman2009-06-03 06:18:56
GoLefty!! Posted June 3, 2009 Posted June 3, 2009 brilliant work Johan! it's an education to see these issues. SOmething I've always done when buying wheels is look at the spoke interface with the rim. Due to most boutique wheels having these issues I have never really bought into the concept. I once fell into the poncy roadie mindset and bought a pair of Ksyrium SSC's.... and I thought they were wonderful.......till I had to replace a spoke. They were race only wheels from that point. I believe Easton makes the most sensible boutique wheels at the moment.
Christopher Brunsdon Posted June 3, 2009 Posted June 3, 2009 Johan, just a Q&A here: If a spoke breaks at the bend side, but never at the threaded side/nipple, what could be the cause of this? (BTW: Will have to do your wheel building course as I want to get into WB - as a hobby.)
steven Posted June 3, 2009 Posted June 3, 2009 JB i read your article with amazing interest and would like to comment as follows as we also get wheels which have been re-built by rocket scientists whom dont follow basic rules.Any re-built wheel should have its spoke tension checked with the correct tensions recommend by the wheel manufacturer.The Shimano hub you mention has offset nipple recesses on the hub flange,the design is meant to transfer the load to the hub from the rim. It seems to us that the wheel was badly built causing the rider to getaggravated with the wheel and having spokes bend which leads to me beleiving that the tension was incorrect to start with. In future let us inspect the wheel and give an opionion before lamblasting the brand. The price quoted for Shimano spokes are incorrect unless you are working with a 200 % mark-up Some wheel manufacturers have addressed quality issues and have updated there models accordingly. I have seen for myself at Shimano in Japan just how much R&D go into wheels and the testing thereafter is mindblowing to say the least. rgds sm www.coolheat.co.za
Johan Bornman Posted June 3, 2009 Author Posted June 3, 2009 Johan' date=' just a Q&A here: If a spoke breaks at the bend side, but never at the threaded side/nipple, what could be the cause of this?(BTW: Will have to do your wheel building course as I want to get into WB - as a hobby.)[/quote'] A spoke breaking at the elbow are fatigue breaks and are usually caused by the lack of stress relieving during build and a too low tension in the spoke. Also, the wheelbuilder should try and make the spoke follow the hub very closely where it comes out of the hole, with no visible gap between spoke and flange. Cheaper hubs without chamfered spoke holes contribute to the problem as does hubs with parallel flanges. Flanges that follow the spoke line reduce the problem. In a well-built wheel you'll occasionally get a spoke that breaks from fatigue and that's usually a defect in that one spoke. If the wheel contintues to break spokes in the same way, the only option is to strip it, rebuild with new spokes and make sure it is stress relieved.
Johan Bornman Posted June 3, 2009 Author Posted June 3, 2009 JB i read your article with amazing interest and would like to comment as follows as we also get wheels which have been re-built by rocket scientists whom dont follow basic rules.Any re-built wheel should have its spoke tension checked with the correct tensions recommend by the wheel manufacturer.The Shimano hub you mention has offset nipple recesses on the hub flange' date='the design is meant to transfer the load to the hub from the rim. It seems to us that the wheel was badly built causing the rider to getaggravated with the wheel and having spokes bend which leads to me beleiving that the tension was incorrect to start with. In future let us inspect the wheel and give an opionion before lamblasting the brand. The price quoted for Shimano spokes are incorrect unless you are working with a 200 % mark-up Some wheel manufacturers have addressed quality issues and have updated there models accordingly. I have seen for myself at Shimano in Japan just how much R&D go into wheels and the testing thereafter is mindblowing to say the least. rgds sm www.coolheat.co.za [/quote'] Dear Steven It saddens me to have you think I lamblast your brand. I think you only need to search for any of my posts with XTR or XT hubs and you'll see something to the contrary. I fact, have a look at the most recent Chris King hub post. I don't attack brands but always state an opinion followed by the facts as I observe them. In this case there is a misalignment between the nipple and spoke line. It is visible in the wheel and clearly visible from the spokes I removed. It is a death knell to spokes. I've posted on this extensively. Search for Spoke Arrival Angle in any of my posts. Great companies also make mistakes. Great companies also come up with less-than-optimal designs from time to time. Hence the change from nipples at the hub to nipples at the rim for Shimano. I have pointed out this same problem with EA70 wheels sometime this year. Search and you'll see. It happens to the best companies and we often see a move away from a specific design. However, no-one ever admits that the previous design was flawed. Especially not Japanese. Hari-kiri is very painful, I believe. The old issue of spoke tension comes up again. None of the issues I describe has anything to do with spoke tension. Misalignment of spoke line and nipple angle cannot be corrected with a tensiometer. All spoke/hub/rim interfaces transfer load. This goes for all wheels, whether they are J-bend, straight-pull or screw-in. Load goes into the hub by pedaling torsion and gets transferred via the spokes and nipples to the rim and ultimately tyre. I don't get your point. It seems to us that the wheel was badly built causing the rider to getaggravated with the wheel and having spokes bend which leads to me beleiving that the tension was incorrect to start with. This really doesn't make sense. Re-read what I described. I think you'll then realise that the only explanation for the bend in the spoke at the thread is a misaligned nipple. There is no way that this wheel can be laced incorrectly without some very, very obviously strange spoke patterns. Finally, don't forget to read between the lines when I jest about engineers. Whilst stating the facts I like to keep my tongue firmly in my cheek. SincerelyJohan PS - I forgot to reply to the issue of cost. The cost of one of those spokes and the nipple is retail: R35.49. This includes a fair mark-up. What am I missing? Johan Bornman2009-06-03 06:10:42
Christopher Brunsdon Posted June 3, 2009 Posted June 3, 2009 Thanks Johan - I purposly left out the fact that this happened to my motorbike as I'm convinced the same rules apply. As mentioned, want to do your WB course and see your doing it September in CT - get my bonus end August so looking forward. I found that locally there are not enough wheel builders, so while the course is pricey I'm sure it is worth it. cbrunsdon2009-06-03 06:32:41
javadude Posted June 3, 2009 Posted June 3, 2009 Thanks Johan - I purposly left out the fact that this happened to my motorbike as I'm convinced the same rules apply. As mentioned' date=' want to do your EB course and see your doing it September in CT - get my end August so looking forward. I found that locally there are not enough wheel builders, so while the course is pricey I'm sure it is worth it. [/quote'] Me too, also want to do the wheel building course.
Flemish Lion Posted June 3, 2009 Posted June 3, 2009 It seems all too easy for Shimano to blame the spoke breakage to the fact that JB did not use a tension meter. JB has a close to 100% success record with his wheel builds. The facts/pics also seem to point out that the spokes will/would keep on breaking, even when tensioned according to Shimano specifications!
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